Solar Energy Materials and Solar Cells | 2021
Resonance absorption and quantum efficiency of graded composition AlxGa1-xN nanowire array cathode
Abstract
Abstract In order to fully utilize the energy of sunlight as much as possible, nanowire array (NWA) photocathodes have begun to be explored. The photoemission capability of the graded composition AlxGa1-xN NWA was studied to solve the problem of “secondary absorption” of escaping electrons by the adjacent nanowires of the NWA photocathode. The results show that the built-in electric field introduced by the graded composition can promote the drift and diffusion of the carriers inside the nanowire to the top surface. The single-component Al0.49Ga0.51N NWA is obtained the highest quantum efficiency at a resonance wavelength of 347\xa0nm, which is approximately 42.81%. However, the graded composition AlxGa1-xN NWA cathode can obtain a quantum efficiency of 62.32% at 274\xa0nm, which not only achieves an increase in quantum efficiency, but also causes a blue shift in the resonance wavelength. Furthermore, the graded composition AlxGa1-xN NWA cathode with a uniform thickness of H\xa0=\xa0700\xa0nm, P\xa0=\xa0300\xa0nm, and D\xa0=\xa0150\xa0nm has a resonance absorption of about 98% and a reflectance of only 1% at the resonance wavelength. The above studies all show that the graded composition AlxGa1-xN NWA cathode can be used as a future candidate core device for vacuum solar blind ultraviolet detectors.